During wash and rinse cycles, dishwasher appliances generally circulate a fluid through a wash chamber over articles, such as pots, pans, silverware, etc. The fluid can be, e.g., various combinations of water and detergent during the wash cycle, or water (which may include additives) during the rinse cycle. Typically, the fluid is circulated during a given cycle using a pump. Fluid is collected at or near the bottom of the wash chamber and pumped back into the wash chamber through, e.g., nozzles in spray arms and other openings that direct the fluid against the articles to be cleaned or rinsed.
Depending upon the level of soil on the articles, fluids used during wash and rinse cycles can become contaminated with soils in the form of debris or particles that are carried with the fluid. In order to protect the pump and recirculate the fluid through the wash chamber, it is beneficial to filter the fluid so that relatively clean fluid is applied to the articles in the wash chamber and soils are removed or reduced from the fluid supplied to the pump.
Accordingly, dishwasher appliances are generally provided with a filter assembly to trap at least certain of the soils carried with the wash fluid. Such filter assemblies generally include a course filter and a fine filter in a parallel flow configuration. For example, during a wash cycle a portion of the recirculated wash fluid may pass through the coarse filter and a portion of the recirculated wash fluid may pass through the fine filter. Through the course of the wash cycle, it is expected that substantially all of the wash fluid will pass through the fine filter, such that eventually all soils larger than a maximum predetermined size (i.e, a size of soils filtered by the fine filter) are removed from the wash fluid.
One issue with such parallel configurations of coarse and fine filters is that during shortened cycles or due to other factors, some soils may not necessarily encounter both sizes of filter. Accordingly, some soils, such as soils small enough to pass through the coarse filter but large enough to be trapped by fine filter, may remain in the wash fluid. Further, larger soils may clog the fine filter if they are trapped by the fine filter before encountering the coarse filter.
Accordingly, improved filter assemblies have been provided for use in dishwasher appliances which utilize a series arrangement of filters, in which the wash fluid progressively flows through filters that have smaller and smaller holes. Additionally, blades may be provided adjacent the filters to generally unclog soil from the filters and guide the soil towards discharge areas. It is generally desirable for these blades to be in close proximity to respective filters to facilitate such cleaning.
While such filter assemblies provide advantages with regard to filtering, improvements could be made with respect to the locating of various elements of the filter assemblies relative to each other. For example, it is important that the blades are located at precise, consistent positions relative to the filters. Further, improvements could also be made with respect to flow of wash fluid through the filters. For example, it is important that the central apertures in the filters, through which a shaft may extend, are sealed to prevent the bypass of soil through such central apertures.
Accordingly, improved filter assemblies are desired. In particular, filter assemblies which provide improved locating and sealing features would be advantageous.